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Oceans Characteristics Features Life Forms The Ocean Floor The ocean floor has higher mountains, deeper canyons, and larger flatter plains. Earthquakes occur more often. The rocks are very different. The crust is thinner. Continental Shelf The continental shelf is the gradually sloping end of a continent that extends under the ocean. The ocean covering the continental shelf can be as deep as 350 m. Large mineral, oil and natural gas deposits are found here. Continental Slope At the edge of the continental shelf, the ocean floor plunges steeply 4 to 5 kilometers. The continental slope extends from the outer edge of the continental shelf down to the ocean floor. Abyssal Plains Large, flat areas on the ocean floor are called abyssal plains. The abyssal plains are larger in the Atlantic and Indian than in the Pacific due to the deposition of sediments by large rivers. The Pacific Ocean has large cracks that trap sediments and result in smaller abyssal plains. Abyssal Plains Abyssal plains are close to the continent and are made of mud, sand and silt. Seamounts Seamounts are underwater volcanic mountains that rise more than 100 meters above the ocean floor. Most have been found in the Pacific Ocean. Some seamounts reach above the surface of the water to form islands, like the Azores in the Atlantic and the Hawaiian islands in the Pacific. Trenches Trenches are the deepest parts of the ocean found along the edge of the ocean floor. The Mariana Trench in the Pacific Ocean contains the deepest spot (1100 meters) on Earth known as Challenger Deep. Mid-ocean Ridges • A mid-ocean ridge is the area in an ocean basin where new ocean floor is formed. The mid-ocean ridges form an almost continuous mountain belt that extends from the Arctic Ocean down through the middle of the Atlantic Ocean around Africa into the Indian Ocean and across the Pacific Ocean. In the Atlantic it is called the mid-Atlantic Ridge and in the Pacific, the PacificAntarctica Ridge. Upwelling Upwelling brings up tiny ocean organisms, minerals, and other nutrients from the deeper layers of the water; without upwelling the surface of the ocean would be nutrient deficient. El Nino El Nino is an abnormal climate event that occurs every 2-7 years in the Pacific Ocean, causing changes in the winds, currents, and weather patterns. El Nino El Nino interrupts up the pattern of upwelling. Without nutrients provided by upwelling, fish and other organisms cannot find food. Fish and other organisms die and weather patterns are disturbed.